Spray Foam Insulation in Soddy-Daisy, TN

Two towns, one lake

Soddy-Daisy is the 1969 union of two old communities, Soddy and Daisy, that grew up on coal and the railroad along the foot of Walden's Ridge. Today it is a long, thin city following US-27 north from Hixson toward Sale Creek, with Chickamauga Lake on the east and the ridge on the west. Soddy Creek, its embayment on the lake, and a string of smaller coves mean a lot of homes sit within a few hundred feet of open water.

The housing is more mixed than in the older inner suburbs. Census Bureau estimates put Soddy-Daisy's median build year at about 1989, with roughly four in ten homes built before 1980 and roughly three in ten built since 2000. That means everything from century-old frame cottages near the old town centers, to 1970s lake houses, to 2000s subdivisions cut into the hillsides west of the highway.

Lake houses and humidity

A house on a Chickamauga Lake cove lives in some of the most humid air in the county. Morning relative humidity averages 85 percent across the Chattanooga area in NOAA's long-term records, and it runs higher right on the water. Lake houses are often built on piers or block crawl spaces open to that air, sometimes with the floor system fully exposed underneath. Fiberglass in those floors is wet within a few seasons.

For a pier or open-crawl lake house, closed-cell foam sprayed directly to the underside of the floor system is the durable answer: it insulates, air-seals and does not absorb moisture. For a block crawl space, full encapsulation with foam on the walls is the better assembly. Either way, the material below the floor has to be one that tolerates wet air, and open-cell foam or batts do not.

Old cottages and new subdivisions

The older frame houses in the Soddy and Daisy town centers usually have little or no wall insulation, minimal attic insulation and open crawl spaces on stone or block. They respond well to a two-part approach: crawl space encapsulation below and a sealed, insulated attic above, with the walls handled during renovation. The newer hillside subdivisions have code-era insulation but the usual vented crawl spaces and attic ducts, and the same crawl space and attic work pays off, particularly on the homes at the bottoms of the slopes where the ground stays wet.

Soddy-Daisy is served by EPB, so the EPB and TVA EnergyRight rebates for attic insulation and air sealing are available under the program's rules. The city issues its own building permits.